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Test available for genetic predisposition to chordoma

Scientists working on the Chordoma Genome Project have identified a genetic variant (a SNP) that causes a five-fold increase in risk of developing chordoma. In a study of 60 Caucasian chordoma patients, they found that over 95% had a misspelling (an A substituted for a G) in the DNA sequence at a particular site of a gene called brachyury. About 75% of patients had two copies of the variant brachyury gene, while the remainder of patients had one normal copy and one variant copy of the gene. (See announcement for more information)

Genetic testing available through sarcoma research

Chordoma patients and family members interested in knowing whether they have the SNP associated with developing chordoma can find out through the DNA analysis service offered by genetic testing company 23andMe.

23andMe offers a mail-order kit for genome-wide SNP testing, which will detect the SNP associated with chordoma. Through a partnership with the Chordoma Foundation, 23andMe is offering free SNP testing to 50 chordoma patients as part of an ongoing study of sarcoma patients. (1/1/2014 – There are no more codes for discounted kits available at this time. Please visit 23andMe to order a kit).

23andMe wants to put the power to make a change in the hands of the patient community. By combining genetic data with survey responses about people’s health and experiences, 23andMe hopes to discover new genetic markers for diseases, understand why some people respond to treatment more readily than others, and explore gene-environment interactions. Join this web-based initiative to advance sarcoma research – submit a saliva sample for DNA and complete online surveys about your sarcoma diagnosis, symptoms, and treatment. There is no cost to participate, and all research steps can be done from home, requiring no travel, visits to a clinic, or invasive procedures. All genetic and non-genetic samples are de-identified for research purposes. As a benefit to participation, you will receive free access to 23andMe’s full Personal Genome Service®, including genetic health and ancestry information.

Chordoma patients who enroll in the study will be asked to take several optional surveys

Completing these surveys will help researchers identify other genetic or environmental risk factors that might be associated with chordoma.

Interpreting Results

Once you submit a saliva sample to 23andMe and receive your genetic testing results you can determine whether you have the chordoma-associated SNP here.

The two versions of the SNP in the brachyury gene are represented in the 23andMe data browser as either C or T (the complement of G and A reported in the paper published on the SNP). C corresponds to the normal form of brachyury while T corresponds to the chordoma-associated variant. Because each individual has two copies of every gene in their genome your genotype for the brachyury gene is represented by a two-letter combination – either CC, CT, or TT.

CC – two normal copies of brachyury

CT – one normal copy and one variant copy of brachyury

TT – two variant copies of brachyury

It is currently not known whether the number of copies of the variant brachyury gene affects prognosis or outcomes for chordoma patients, and right now it will not affect the treatment of chordoma patients.

Individuals who have the chordoma-associated SNP but do not have chordoma are roughly five times more likely to develop chordoma than people who do not have the chordoma-associated SNP. However, even for individuals who have the SNP, the chance of getting chordoma is still exceedingly low. At this point, there is nothing known to reduce the risk of developing chordoma. If you are concerned about your risk of getting chordoma, talk to your doctor.

For more information about what the SNP means for chordoma patients and the future of chordoma research see our Q&A on the SNP discovery.

Note: the information on this page has not yet been evaluated by 23andMe and is being provided independently by the Chordoma Foundation.